Researchers reported long-term results from a multicentre gene therapy trial targeting autosomal recessive deafness 9 (DFNB9), a severe congenital hearing loss caused by mutations in OTOF. The findings, published in Nature in 2026, described sustained safety and efficacy over extended follow-up. The results build on earlier clinical evidence that gene therapy can produce durable hearing improvements when delivered early enough for auditory pathway development. The multicentre design increases the weight of the evidence base by demonstrating consistency across sites rather than single-cohort signals. For the gene therapy market, DFNB9 is an important benchmark because it sits in a high-need segment where sensory outcomes are clear endpoints for efficacy and where durability is a core question. The long-term dataset supports ongoing momentum in audiology gene therapy development and informs how manufacturers and regulators may view extended follow-up requirements for future programs.